DOCSLIB.ORG

GPS Applications in Space

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
GPS Applications in Space Space Situational Awareness 2015: GPS Applications in Space James J. Miller, Deputy Director Policy & Strategic Communications Division May 13, 2015 GPS Extends the Reach of NASA Networks to Enable New Space Ops, Science, and Exploration Apps GPS Relative Navigation is used for Rendezvous to ISS GPS PNT Services Enable: • Attitude Determination: Use of GPS enables some missions to meet their attitude determination requirements, such as ISS • Real-time On-Board Navigation: Enables new methods of spaceflight ops such as rendezvous & docking, station- keeping, precision formation flying, and GEO satellite servicing • Earth Sciences: GPS used as a remote sensing tool supports atmospheric and ionospheric sciences, geodesy, and geodynamics -- from monitoring sea levels and ice melt to measuring the gravity field ESA ATV 1st mission JAXA’s HTV 1st mission Commercial Cargo Resupply to ISS in 2008 to ISS in 2009 (Space-X & Cygnus), 2012+ 2 Growing GPS Uses in Space: Space Operations & Science • NASA strategic navigation requirements for science and 20-Year Worldwide Space Mission space ops continue to grow, especially as higher Projections by Orbit Type* precisions are needed for more complex operations in all space domains 1% 5% Low Earth Orbit • Nearly 60%* of projected worldwide space missions 27% Medium Earth Orbit over the next 20 years will operate in LEO 59% GeoSynchronous Orbit – That is, inside the Terrestrial Service Volume (TSV) 8% Highly Elliptical Orbit Cislunar / Interplanetary • An additional 35%* of these space missions that will operate at higher altitudes will remain at or below GEO – That is, inside the GPS/GNSS Space Service Volume (SSV) Highly Elliptical Orbits**: • In summary, approximately 95% of projected Example: NASA MMS 4- worldwide space missions over the next 20 years will satellite constellation. operate within the GPS service envelope (**) Apogee above GEO/GSO (*) Source: Aerospace America, American Institute of Aeronautics and Astronautics (AIAA), Dec. 2007 Medium Earth Orbit: Orbital Transfers: LEO-to- GNSS Constellations, GSO, cislunar transfer orbit, etc., transplanetary injection, etc. GeoSynchronous: 3 Communication Satellites, etc., GPS Space Service Volume (SSV) Concept Partnership with DoD Space Service Volume (Medium Altitudes) • Four GNSS signals available simultaneously a majority of the time • GNSS signals over the limb of the earth become increasingly important with altitude • One-meter orbit accuracies Space Service Volume (High Altitudes) • Nearly all GNSS signals are received over the limb of the Earth • Periods when no signals are available • Signal levels will be weaker than those in Terrestrial Service Volume (TSV) • Positioning software uses orbital physics, and/or stable on-board oscillators, to achieve orbit accuracy of tens of meters 4 Space Service Volume: Using GPS Beyond LEO and up to GeoSynchronous Altitude • 3,000 to 8,000 km Medium Altitudes –Four GPS signals usually available simultaneously, however poor geometry & coverage gaps cause harm –1 meter accuracies still feasible, however space GPS receivers have more difficulty processing signals –GPS performance degrades with altitude due to geometry and classic near/far problem • 8,000 to 36,000 km High Altitudes –Users will experience periods when no GPS satellites are available – Point Positioning no longer available –Nearly all GPS signals received over limb of the Earth – High variability in signal strength and beam paths –Received power levels are weaker than those in TSV or MEO SSV – Side Lobe processing needed –Specially designed receivers will be capable of maintaining accuracies ranging from 10- 100 meters depending on receiver 5 sensitivity and local oscillator stability 5 Expanding the GPS Space Service Volume (SSV) into a multi-GNSS SSV • At least four GNSS satellites in line-of-sight are ≥ 4 GPS satellites in line-of-sight here needed for on-board real-time autonomous (surface to 3000 km) navigation – GPS currently provides this up to 3,000 km altitude – Enables better than 1-meter position accuracy in real-time • At GSO altitude, only one GPS satellite will be available at any given time. – GPS-only positioning at GSO is still possible with on- board processing, but only up to approx. 100-meter absolute position accuracy. – GPS + Galileo combined would enable 2-3 GNSS sats in-view at all times. – GPS + Galileo + GLONASS would enable at least 4 GNSS sats in-view at all times. – GPS + Galileo + GLONASS + Beidou would enable > 4 GNSS sats in view at all times. This provides best accuracy and, also, on-board integrity. Only 1-2 GPS ... but, if interoperable, • However, this requires: satellites in then GPS + Galileo + – Interoperability among these the GNSS line-of-sight GLONASS + Beidou provide constellations; and – Common definitions/specifications for the Space here (GSO) > 4 GNSS sats in line-of- Service Volume (3,000 km to GSO altitude) sight at GSO 6 Using GPS above the GPS Constellation: NASA MMS Mission – GSFC Team Info Magnetospheric Multi-Scale (MMS) Mission • Launched March 12, 2015 • Four spacecraft form a tetrahedron near apogee for performing magnetospheric science measurements (space weather) • Four spacecraft in highly eccentric orbits – Phase 1: 1.2 x 12 Earth Radii (Re) Orbit (7,600 km x 76,000 km) – Phase 2: Extends apogee to 25 Re (~150,000 km) MMS Navigator System • GPS enables onboard (autonomous) navigation and potentially autonomous station-keeping • The MMS Navigator system exceeded all of the team’s expectations, it has set the record for the highest GPS use in space • At the highest point of the MMS orbit Navigator set a record for the highest-ever reception of signals and onboard navigation solutions by an operational GPS receiver in space • At the lowest point of the MMS orbit Navigator set a record as the fastest operational GPS receiver in space, at velocities over 35,000 km/h 7 MMS Navigator System: Initial Observations • In the first month after launch, the MMS team began turning on and testing each instrument and deploying booms and antennas. – During this time, the team compared the Navigator system with ground tracking systems and found it to be even more accurate than expected – At the farthest point in its orbit, some 76,000 km from Earth, Navigator can determine the position of each spacecraft with an uncertainty of better than 15 meters – The receivers on MMS have turned out to be strong enough that they consistently track transmissions from eight to 12 GPS satellites – excellent performance when compared to pre-flight predictions of frequent drop outs during each orbit 8 Why is the Space Service Volume Important? SSV specifications are crucial for providing real-time GNSS navigation solutions in High Earth Orbit • Supports increased satellite autonomy for missions, lowering mission operations costs • Significantly improves vehicle navigation performance in these orbits • Enables new/enhanced capabilities and better performance for future missions, such as: Improved Weather Prediction using Space Weather Observations Astrophysics Observations Advanced Weather Satellites En-route Lunar Formation Flying & Closer Spacing of Satellites in 9 Navigation Support Constellation Missions Geostationary Arc Satellite Laser Ranging (SLR) on GPS III • Laser ranging to GNSS satellites enables the comparison of optical laser measurements with radiometric data, Satellite Orbit Laser Reflector Array identifying systemic errors on a Satellite • Post-processing this data allows for refining station coordinates, satellite orbits, and timing epochs • The refined data enables improved models and reference frames Laser Pulse • This results in higher PNT accuracies for all users, while enhancing interoperability amongst constellations • NASA Administrator Bolden worked with Air Force Gen Laser Ranging Shelton & Gen Kehler to approve Laser Reflector Arrays Station (LRAs) onboard GPS III • Plans are now underway to deploy LRAs on GPS III starting Laser pulse (start) with Space Vehicle 9 for launch in the 2020 timeframe Photon return (stop) Measurement of round trip time of laser pulse Station coordinate and satellite orbit 10 determination relative to Earth’s center Augmenting GPS in Space with TASS TDRSS Augmentation Satellite Service (TASS) 1) User Acquires GPS signals GEO Relay 2) GDGPS Tracks GPS signals Satellite 3) GEO Satellite Relays Differential 4) Evolved TASS could Corrections to User incorporate: • GPS integrity information • Tracking satellite GPS Satellites information (health, ephemerides, maneuvers) • Space weather data • Solar flux data • Earth orientation parameters Space User • User-specific commands • PRN ranging code GDGPS Network 11 11 Closing Remarks • NASA and other space users increasingly rely on GPS/GNSS over an expanding range of orbital applications to serve Earth populations in countless ways • The United States will continue to work towards maintaining GPS as the “gold standard” as other international PNT constellations come online • NASA is proud to work with the USAF to contribute making GPS services more accessible, interoperable, precise, and robust for all appropriate users • GPS precision enables incredible science, which in turn allows NASA to use this science to improve GPS performance “On Target with GPS Video” www.youtube.com/watch?v=_zM79vSnD2M 12 .
Load more

Recommended publications
  • Analysis of Perturbations and Station-Keeping Requirements in Highly-Inclined Geosynchronous Orbits
    ANALYSIS OF PERTURBATIONS AND STATION-KEEPING REQUIREMENTS IN HIGHLY-INCLINED GEOSYNCHRONOUS ORBITS Elena Fantino(1), Roberto Flores(2), Alessio Di Salvo(3), and Marilena Di Carlo(4) (1)Space Studies Institute of Catalonia (IEEC), Polytechnic University of Catalonia (UPC), E.T.S.E.I.A.T., Colom 11, 08222 Terrassa (Spain), [email protected] (2)International Center for Numerical Methods in Engineering (CIMNE), Polytechnic University of Catalonia (UPC), Building C1, Campus Norte, UPC, Gran Capitan,´ s/n, 08034 Barcelona (Spain) (3)NEXT Ingegneria dei Sistemi S.p.A., Space Innovation System Unit, Via A. Noale 345/b, 00155 Roma (Italy), [email protected] (4)Department of Mechanical and Aerospace Engineering, University of Strathclyde, 75 Montrose Street, Glasgow G1 1XJ (United Kingdom), [email protected] Abstract: There is a demand for communications services at high latitudes that is not well served by conventional geostationary satellites. Alternatives using low-altitude orbits require too large constellations. Other options are the Molniya and Tundra families (critically-inclined, eccentric orbits with the apogee at high latitudes). In this work we have considered derivatives of the Tundra type with different inclinations and eccentricities. By means of a high-precision model of the terrestrial gravity field and the most relevant environmental perturbations, we have studied the evolution of these orbits during a period of two years. The effects of the different perturbations on the constellation ground track (which is more important for coverage than the orbital elements themselves) have been identified. We show that, in order to maintain the ground track unchanged, the most important parameters are the orbital period and the argument of the perigee.
    [Show full text]
  • Astrodynamics
    Politecnico di Torino SEEDS SpacE Exploration and Development Systems Astrodynamics II Edition 2006 - 07 - Ver. 2.0.1 Author: Guido Colasurdo Dipartimento di Energetica Teacher: Giulio Avanzini Dipartimento di Ingegneria Aeronautica e Spaziale e-mail: [email protected] Contents 1 Two–Body Orbital Mechanics 1 1.1 BirthofAstrodynamics: Kepler’sLaws. ......... 1 1.2 Newton’sLawsofMotion ............................ ... 2 1.3 Newton’s Law of Universal Gravitation . ......... 3 1.4 The n–BodyProblem ................................. 4 1.5 Equation of Motion in the Two-Body Problem . ....... 5 1.6 PotentialEnergy ................................. ... 6 1.7 ConstantsoftheMotion . .. .. .. .. .. .. .. .. .... 7 1.8 TrajectoryEquation .............................. .... 8 1.9 ConicSections ................................... 8 1.10 Relating Energy and Semi-major Axis . ........ 9 2 Two-Dimensional Analysis of Motion 11 2.1 ReferenceFrames................................. 11 2.2 Velocity and acceleration components . ......... 12 2.3 First-Order Scalar Equations of Motion . ......... 12 2.4 PerifocalReferenceFrame . ...... 13 2.5 FlightPathAngle ................................. 14 2.6 EllipticalOrbits................................ ..... 15 2.6.1 Geometry of an Elliptical Orbit . ..... 15 2.6.2 Period of an Elliptical Orbit . ..... 16 2.7 Time–of–Flight on the Elliptical Orbit . .......... 16 2.8 Extensiontohyperbolaandparabola. ........ 18 2.9 Circular and Escape Velocity, Hyperbolic Excess Speed . .............. 18 2.10 CosmicVelocities
    [Show full text]
  • GPS and GLONASS Vector Tracking for Navigation in Challenging Signal Environments
    GPS and GLONASS Vector Tracking for Navigation in Challenging Signal Environments Tanner Watts, Scott Martin, and David Bevly GPS and Vehicle Dynamics Lab – Auburn University October 29, 2019 2 GPS Applications (GAVLAB) Truck Platooning Good GPS Signal Environment Autonomous Vehicles Precise Timing UAVs 3 Challenging Signal Environments • Navigation demand increasing in the following areas: • Cites/Urban Areas • Forests/Dense Canopies • Blockages (signal attenuation) • Reflections (multipath) 4 Contested Signal Environments • Signal environment may experience interference • Jamming . Transmits “noise” signals to receiver . Effectively blocks out GPS • Spoofing . Transmits fake GPS signals to receiver . Tricks or may control the receiver 5 Contested Signal Environments • These interference devices are becoming more accessible GPS Jammers GPS Simulators 6 Traditional GPS Receiver Signals processed individually: • Known as Scalar Tracking • Delay Lock Loop (DLL) for Code • Phase Lock Loop (PLL) for Carrier 7 Traditional GPS Receiver • Feedback loops fail in the presence of significant noise • Especially at high dynamics Attenuated or Distorted Satellite Signal 8 Vector Tracking Receiver • Process signals together through the navigation solution • Channels track each other’s signals together • 2-6 dB improvement • Requires scalar tracking initially 9 Vector Tracking Receiver Vector Delay Lock Loop (VDLL) • Code tracking coupled to position navigation • DLL discriminators inputted into estimator • Code frequencies commanded by predicted pseudoranges
    [Show full text]
  • Comparing Four Methods of Correcting GPS Data: DGPS, WAAS, L-Band, and Postprocessing Dick Karsky, Project Leader
    United States Department of Agriculture Engineering Forest Service Technology & Development Program July 2004 0471-2307–MTDC 2200/2300/2400/3400/5100/5300/5400/ 6700/7100 Comparing Four Methods of Correcting GPS Data: DGPS, WAAS, L-Band, and Postprocessing Dick Karsky, Project Leader he global positioning system (GPS) of satellites DGPS Beacon Corrections allows persons with standard GPS receivers to know where they are with an accuracy of 5 meters The U.S. Coast Guard has installed two control centers Tor so. When more precise locations are needed, and more than 60 beacon stations along the coastal errors (table 1) in GPS data must be corrected. A waterways and in the interior United States to transmit number of ways of correcting GPS data have been DGPS correction data that can improve GPS accuracy. developed. Some can correct the data in realtime The beacon stations use marine radio beacon fre- (differential GPS and the wide area augmentation quencies to transmit correction data to the remote GPS system). Others apply the corrections after the GPS receiver. The correction data typically provides 1- to data has been collected (postprocessing). 5-meter accuracy in real time. In theory, all methods of correction should yield similar In principle, this process is quite simple. A GPS receiver results. However, because of the location of different normally calculates its position by measuring the time it reference stations, and the equipment used at those takes for a signal from a satellite to reach its position. stations, the different methods do produce different Because the GPS receiver knows exactly where results.
    [Show full text]
  • AFSPC-CO TERMINOLOGY Revised: 12 Jan 2019
    AFSPC-CO TERMINOLOGY Revised: 12 Jan 2019 Term Description AEHF Advanced Extremely High Frequency AFB / AFS Air Force Base / Air Force Station AOC Air Operations Center AOI Area of Interest The point in the orbit of a heavenly body, specifically the moon, or of a man-made satellite Apogee at which it is farthest from the earth. Even CAP rockets experience apogee. Either of two points in an eccentric orbit, one (higher apsis) farthest from the center of Apsis attraction, the other (lower apsis) nearest to the center of attraction Argument of Perigee the angle in a satellites' orbit plane that is measured from the Ascending Node to the (ω) perigee along the satellite direction of travel CGO Company Grade Officer CLV Calculated Load Value, Crew Launch Vehicle COP Common Operating Picture DCO Defensive Cyber Operations DHS Department of Homeland Security DoD Department of Defense DOP Dilution of Precision Defense Satellite Communications Systems - wideband communications spacecraft for DSCS the USAF DSP Defense Satellite Program or Defense Support Program - "Eyes in the Sky" EHF Extremely High Frequency (30-300 GHz; 1mm-1cm) ELF Extremely Low Frequency (3-30 Hz; 100,000km-10,000km) EMS Electromagnetic Spectrum Equitorial Plane the plane passing through the equator EWR Early Warning Radar and Electromagnetic Wave Resistivity GBR Ground-Based Radar and Global Broadband Roaming GBS Global Broadcast Service GEO Geosynchronous Earth Orbit or Geostationary Orbit ( ~22,300 miles above Earth) GEODSS Ground-Based Electro-Optical Deep Space Surveillance
    [Show full text]
  • GLONASS & GPS HW Designs
    GLONASS & GPS HW designs Recommendations with u-blox 6 GPS receivers Application Note Abstract This document provides design recommendations for GLONASS & GPS HW designs with u-blox 6 module or chip designs. u-blox AG Zürcherstrasse 68 8800 Thalwil Switzerland www.u-blox.com Phone +41 44 722 7444 Fax +41 44 722 7447 [email protected] GLONASS & GPS HW designs - Application Note Document Information Title GLONASS & GPS HW designs Subtitle Recommendations with u-blox 6 GPS receivers Document type Application Note Document number GPS.G6-CS-10005 Document status Preliminary This document and the use of any information contained therein, is subject to the acceptance of the u-blox terms and conditions. They can be downloaded from www.u-blox.com. u-blox makes no warranties based on the accuracy or completeness of the contents of this document and reserves the right to make changes to specifications and product descriptions at any time without notice. u-blox reserves all rights to this document and the information contained herein. Reproduction, use or disclosure to third parties without express permission is strictly prohibited. Copyright © 2011, u-blox AG. ® u-blox is a registered trademark of u-blox Holding AG in the EU and other countries. GPS.G6-CS-10005 Page 2 of 16 GLONASS & GPS HW designs - Application Note Contents Contents .............................................................................................................................. 3 1 Introduction .................................................................................................................
    [Show full text]
  • AEN-88: the Global Positioning System
    AEN-88 The Global Positioning System Tim Stombaugh, Doug McLaren, and Ben Koostra Introduction cies. The civilian access (C/A) code is transmitted on L1 and is The Global Positioning System (GPS) is quickly becoming freely available to any user. The precise (P) code is transmitted part of the fabric of everyday life. Beyond recreational activities on L1 and L2. This code is scrambled and can be used only by such as boating and backpacking, GPS receivers are becoming a the U.S. military and other authorized users. very important tool to such industries as agriculture, transporta- tion, and surveying. Very soon, every cell phone will incorporate Using Triangulation GPS technology to aid fi rst responders in answering emergency To calculate a position, a GPS receiver uses a principle called calls. triangulation. Triangulation is a method for determining a posi- GPS is a satellite-based radio navigation system. Users any- tion based on the distance from other points or objects that have where on the surface of the earth (or in space around the earth) known locations. In the case of GPS, the location of each satellite with a GPS receiver can determine their geographic position is accurately known. A GPS receiver measures its distance from in latitude (north-south), longitude (east-west), and elevation. each satellite in view above the horizon. Latitude and longitude are usually given in units of degrees To illustrate the concept of triangulation, consider one satel- (sometimes delineated to degrees, minutes, and seconds); eleva- lite that is at a precisely known location (Figure 1). If a GPS tion is usually given in distance units above a reference such as receiver can determine its distance from that satellite, it will have mean sea level or the geoid, which is a model of the shape of the narrowed its location to somewhere on a sphere that distance earth.
    [Show full text]
  • A Highly Elliptical Orbit Space System for Hydrometeorological Monitoring of the Arctic Region by V
    A highly elliptical orbit space system for hydrometeorological monitoring of the Arctic region by V. V. Asmus1, V. N. Dyadyuchenko2, Y. I. Nosenko3, G. M. Polishchuk4 and V. A. Selin3 The lack of reliable, frequently high latitudes. It has therefore been • Monitoring of climate change updated information on the Earth’s suggested that demonstration of polar ice caps is a signifi cant problem a hydrometeorological system of • Data collection and relay for weather forecasting, affecting satellites on highly elliptical orbit from land-, sea- and air-based forecast skill for the entire planet. The (HEO), called the “Arctica” system, observing platforms poor numerical weather prediction should be created to provide the (NWP) skill for the Arctic region necessary complex information for the • Exchange and dissemination of and the Earth’s northern territories diffi cult tasks involved in developing processed hydrometeorological is caused primarily by errors in the whole Arctic region. and heliogeophysical data. determining initial conditions, which depend on the quality of initial Signifi cantly, the hydrometeorological Further progress in global and data. Until now, initial data have observations carried out in the regional numerical weather prediction been received from meteorological Arctic within the framework of the depends to a large extent on: geostationary satellites, which are International Polar Year 2007-2008 not very effective in scanning high are not provided with remote-sensing • Quasi-continuous reception latitudes and polar-orbiting
    [Show full text]
  • NASA Process for Limiting Orbital Debris
    NASA-HANDBOOK NASA HANDBOOK 8719.14 National Aeronautics and Space Administration Approved: 2008-07-30 Washington, DC 20546 Expiration Date: 2013-07-30 HANDBOOK FOR LIMITING ORBITAL DEBRIS Measurement System Identification: Metric APPROVED FOR PUBLIC RELEASE – DISTRIBUTION IS UNLIMITED NASA-Handbook 8719.14 This page intentionally left blank. Page 2 of 174 NASA-Handbook 8719.14 DOCUMENT HISTORY LOG Status Document Approval Date Description Revision Baseline 2008-07-30 Initial Release Page 3 of 174 NASA-Handbook 8719.14 This page intentionally left blank. Page 4 of 174 NASA-Handbook 8719.14 This page intentionally left blank. Page 6 of 174 NASA-Handbook 8719.14 TABLE OF CONTENTS 1 SCOPE...........................................................................................................................13 1.1 Purpose................................................................................................................................ 13 1.2 Applicability ....................................................................................................................... 13 2 APPLICABLE AND REFERENCE DOCUMENTS................................................14 3 ACRONYMS AND DEFINITIONS ...........................................................................15 3.1 Acronyms............................................................................................................................ 15 3.2 Definitions .........................................................................................................................
    [Show full text]
  • Open Rosen Thesis.Pdf
    THE PENNSYLVANIA STATE UNIVERSITY SCHREYER HONORS COLLEGE DEPARTMENT OF AEROSPACE ENGINEERING END OF LIFE DISPOSAL OF SATELLITES IN HIGHLY ELLIPTICAL ORBITS MITCHELL ROSEN SPRING 2019 A thesis submitted in partial fulfillment of the requirements for a baccalaureate degree in Aerospace Engineering with honors in Aerospace Engineering Reviewed and approved* by the following: Dr. David Spencer Professor of Aerospace Engineering Thesis Supervisor Dr. Mark Maughmer Professor of Aerospace Engineering Honors Adviser * Signatures are on file in the Schreyer Honors College. i ABSTRACT Highly elliptical orbits allow for coverage of large parts of the Earth through a single satellite, simplifying communications in the globe’s northern reaches. These orbits are able to avoid drastic changes to the argument of periapse by using a critical inclination (63.4°) that cancels out the first level of the geopotential forces. However, this allows the next level of geopotential forces to take over, quickly de-orbiting satellites. Thus, a balance between the rate of change of the argument of periapse and the lifetime of the orbit is necessitated. This thesis sets out to find that balance. It is determined that an orbit with an inclination of 62.5° strikes that balance best. While this orbit is optimal off of the critical inclination, it is still near enough that to allow for potential use of inclination changes as a deorbiting method. Satellites are deorbited when the propellant remaining is enough to perform such a maneuver, and nothing more; therefore, the less change in velocity necessary for to deorbit, the better. Following the determination of an ideal highly elliptical orbit, the different methods of inclination change is tested against the usual method for deorbiting a satellite, an apoapse burn to lower the periapse, to find the most propellant- efficient method.
    [Show full text]
  • GEO, MEO, and LEO How Orbital Altitude Impacts Network Performance in Satellite Data Services
    GEO, MEO, AND LEO How orbital altitude impacts network performance in satellite data services COMMUNICATION OVER SATELLITE “An entire multi-orbit is now well accepted as a key enabler across the telecommunications industry. Satellite networks can supplement existing infrastructure by providing global reach satellite ecosystem is where terrestrial networks are unavailable or not feasible. opening up above us, But not all satellite networks are created equal. Providers offer different solutions driving new opportunities depending on the orbits available to them, and so understanding how the distance for high-performance from Earth affects performance is crucial for decision making when selecting a satellite service. The following pages give an overview of the three main orbit gigabit connectivity and classes, along with some of the principal trade-offs between them. broadband services.” Stewart Sanders Executive Vice President of Key terms Technology at SES GEO – Geostationary Earth Orbit. NGSO – Non-Geostationary Orbit. NGSO is divided into MEO and LEO. MEO – Medium Earth Orbit. LEO – Low Earth Orbit. HTS – High Throughput Satellites designed for communication. Latency – the delay in data transmission from one communication endpoint to another. Latency-critical applications include video conferencing, mobile data backhaul, and cloud-based business collaboration tools. SD-WAN – Software-Defined Wide Area Networking. Based on policies controlled by the user, SD-WAN optimises network performance by steering application traffic over the most suitable access technology and with the appropriate Quality of Service (QoS). Figure 1: Schematic of orbital altitudes and coverage areas GEOSTATIONARY EARTH ORBIT Altitude 36,000km GEO satellites match the rotation of the Earth as they travel, and so remain above the same point on the ground.
    [Show full text]
  • Orbital Debris Mitigation Standard Practices (ODMSP) Were Established in 2001 to Address the Increase in Orbital Debris in the Near-Earth Space Environment
    U.S. Government Orbital Debris Mitigation Standard Practices, November 2019 Update PREAMBLE The United States Government (USG) Orbital Debris Mitigation Standard Practices (ODMSP) were established in 2001 to address the increase in orbital debris in the near-Earth space environment. The goal of the ODMSP was to limit the generation of new, long-lived debris by the control of debris released during normal operations, minimizing debris generated by accidental explosions, the selection of safe flight profile and operational configuration to minimize accidental collisions, and postmission disposal of space structures. While the original ODMSP adequately protected the space environment at the time, the USG recognizes that it is in the interest of all nations to minimize new debris and mitigate effects of existing debris. This fact, along with increasing numbers of space missions, highlights the need to update the ODMSP and to establish standards that can inform development of international practices. This 2019 update includes improvements to the original objectives as well as clarification and additional standard practices for certain classes of space operations. The improvements consist of a quantitative limit on debris released during normal operations, a probability limit on accidental explosions, probability limits on accidental collisions with large and small debris, and a reliability threshold for successful postmission disposal. The new standard practices established in the update include the preferred disposal options for immediate removal of structures from the near-Earth space environment, a low-risk geosynchronous Earth orbit (GEO) transfer disposal option, a long-term reentry option, and improved move-away-and-stay-away storage options in medium Earth orbit (MEO) and above GEO.
    [Show full text]